1) Three apartment buildings with 196 housing units had their water usage monitored using an I meter solution which installed sensors on each unit's water lines to measure usage at the household level. 2) The sensors recorded data that was read monthly to generate water bills for individual households and analyze usage, helping reduce tanker water demand by 44%. 3) The system measured water at the block level using primary meters on the borewells and overhead tanks, and at the unit level with sub-meters on each apartment's kitchen and bathroom lines.

1. Water Sub-metering @
Nester Raga
Best Practices in Water Management in the Urban Residential Sector

2. Background
 3 apartment buildings, with a total of 196 housing units
 Fresh Water Demand of roughly 128 lpcd
 22.5% demand is met by tankers
 Remainder is met by 2 functioning borewells, BWSSB line not operational
 Treated wastewater is reused for flushing
 I meter solution has been installed to measure the use at the household level
 The system is equipped Automatic meter reading (AMR) devices.
 The data is used to generate monthly water bills for individual households

3. Approach
 The water is measured at two levels, the primary meters and sub-meters.
Primary Meters
• 2 inch meters installed at the OHT
• Capture the usage at a block level
• 11/2 inch metes at output from the bore wells
• Manual verification of total fresh water usage
Sub-meters
• I meter sensor installed on each end-use line
• 3 lines for each apartment
• Raw data recorded by an aggregator on the roof
• Read using a handheld device
• Billing and analysis is provided monthly

4. Sub-metering Layout

5. Water Sub-metering
Each apartment has 3 supply lines, one for the kitchen and one for
each bathroom.
Each line is sub-metered using an I meter sensor .
Meters are installed at the outlet of the borewells and at the Overhead
Tanks for each Block
Sensors are connected via cable to a RF based Automatic Meter
Reading module, each module supports 3 sensors.
It records the data and is read using a portable reader once a month.
The common areas are also sub-metered using the same I meter
technology

6. Learnings
 Manual meters measure the supply and are used to verify the total water
consumed
 Installation was easy, requiring few plumbing modifications
 The tanker demand has reduced by nearly 44% since the summer of 2013
 Current cost of the solution would work up to Rs. 28,000 per apartment
 An android application for monitoring readings, billing and analysis has been
developed as well
 For more information on sub-metering visit www.imetersolutions.com or call Mr.
Vinod Damodaran on 8904068003